CRISPR

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Transcript of CRISPR

Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)CRISPR-CAS-first discovered in bacteria (E.coli, 1987) and functions as a defense against foreign DNA, either viral or plasmid.

-2007, realization that these clustered repeated sequence operated as a safeguard against bacteriophages - a virus that infects and replicates within a bacteria

History 1. the endogenous CRISPR/Cas system targets foreign DNA with a short, complementary single-stranded RNA (CRISPR RNA or crRNA) that localizes the Cas9 nuclease to the target DNA sequence.Process MonkeysCataracts in MiceHIVCystic Fibrosis CancerFunding and ExamplesCRISPR Associated Genes System (CAS)Three distinct Bacterial CRISPR systems Type IType II -basis for genome engineering tool Type IIIThis new system uses a short RNA to guide a nuclease to the DNA target.the DNA target sequence -on a plasmid or integrated into the bacterial genome. -does not need to be unique and can appear in multiple locations,The DSB results in the silencing of that DNA sequence.2. The crRNA can bind on either strand of DNA and the Cas9 will cleave both strands (double strand break, DSB)PhotospacersThe crRNA targeting sequences are transcribed from DNA sequences known as protospacers- clustered in the bacterial genome in a group called a CRISPR array-short sequences of known foreign DNA separated by a short palindromic repeat and kept like a record against future encounters....continuedTo create the CRISPR targeting RNA (crRNA), the array is transcribed and the RNA is processed to separate the individual recognition sequences between the repeats.this changes the sequences of the disease-causing mutant allele! Cat